The treatment of prostate cancer by endocrine therapy induces histological changes of benign or malignant prostate glands. Treated cancers often have a more suspicious architecture, resulting in a higher Gleason score, while their nuclear grade (WHO) appears to be more reliable due to a reduction of the size of nuclei. Most authors appear to agree that cancers discovered by biopsy in patients treated with endocrine therapy should not be graded. A review of the literature appears to indicate that finasteride has less marked histomorphological consequences than other hormone-suppressor treatments and could have a lesser effect on the Gleason score. This paper, based on a review of the literature on this subject, emphasizes: (1) the extent of histological changes after androgen deprivation endocrine therapy; (2) histological changes after Finasteride and the difficulties of histological interpretation, particularly the risk of overestimating the Gleason histoprognostic score; (3) the need for urologists to indicate any treatment by 5-alpha-reductase inhibitors or androgen deprivation when requesting histological examination; (4) the value of collecting and documenting cases observed in the Uropathology Club in collaboration with the Oncology committee of the Association Française d'Urologie.